Answer :
Final answer:
Diffusion welding, friction stir welding, and roll welding are classified as solid-state welding processes because they join materials without melting the base materials.The correct option is A. diffusion welding,
Explanation:
The question is asking which of the processes listed are classified as solid-state welding. Solid-state welding is a group of welding processes that produce coalescence at temperatures essentially below the melting point of the base materials being welded, without the addition of a brazing filler metal. The three processes that fall under this category from the options provided are A. diffusion welding, B. friction stir welding, and D. roll welding.
Diffusion welding involves the use of pressure and elevated temperature to promote diffusion across the interface to be bonded without melting the base material.Friction stir welding uses a non-consumable tool to generate frictional heat and plastic deformation at the welding interface, thereby joining the materials in the solid state.Roll welding entails passing metal sheets between rollers under enough pressure to bond the layers.
Diffusion weldingFriction stir weldingRoll weldingThese processes involve joining metals without the need for melting. Diffusion welding uses pressure and heat, friction stir welding uses frictional heat, and roll welding involves rolling the materials together.
